In general, a DC/AC converter that performs bidirectional conversion between DC power and AC power is used in a three-phase full bridge using a switching element such as an IGBT. The three-phase full bridge is used as a PWM converter.
Meanwhile, in Patent Document 1, a device for driving a DC motor, to which, for example, a three-phase/three-phase matrix converter is applied, is disclosed as a device that performs conversion between AC power and DC power using a matrix converter. Specifically, two pieces of output of a general three-phase/three-phase matrix converter are supplied to an armature of the DC motor, and third output of the three-phase/three-phase matrix converter is connected to a field circuit of the DC motor and is additionally connected to each phase of an input power line via a diode to which a phase corresponds.
In addition, a power converter that directly converts to AC power, without converting AC power to DC power, is also known as a matrix converter, in general. In the matrix converter, a switching element that performs conversion is one stage. Consequently, efficiency can be enhanced compared to a power converter obtained by combining a converter and an inverter. Since there is no circuit that deals with a DC voltage, a smoothing capacitor is not requested, the life of a device can be extended, and reliability can be enhanced. For example, a matrix converter that directly converts input three-phase AC power to three-phase AC power and outputs to a load is disclosed in Patent Document 2.